If the hair of the Bichon Frize puppy is generally yellow, it is abnormal. It is probably caused by not bathing for a long time or improper diet. You can feed the dog some food rich in vitamins B, E, and D. , and usually take the Bichon outside to play and bask in the sun. If the Bichon Frize's hair is only partially yellowed, it may be because the area has been wet for a long time. This requires the owner to dry the dog in time after drinking water or taking a bath to avoid inducing skin damage. Disease, of course, sometimes it is unavoidable that dogs drool and splash urine, which can also cause yellowing of hair.